In order to make appearance of golf balls beautiful and to prevent stain from adhering to the surface of the golf ball, the surface of the golf ball is coated with enamel and clear paint or coated only with clear paint.
As a method capable of coating the golf ball with enamel paint or clear paint by one coating, an air gun coating has hitherto been used. According to the air gun coating, the whole golf ball can be coated with a paint by moving the air gun vertically.
However, the air gun coating process has the problem that the coated film is not uniform, which results in a deterioration of appearance.
Further, in a disc type electrostatic coating wherein paint is coated on an article to be coated from a front direction, there can be used a method capable of coating with enamel paint or clear paint by a single coating. In this electrostatic coating, since the golf ball has no electric conductivity, a conductive agent obtained by diluting a quaternary ammonium salt with alcohol is applied on the surface of the golf ball and, after drying, the golf ball is grounded by placing thereon three metal needles to impart electroconductivity to the golf ball. After the golf ball is subjected to the above electroconducting treatment, a charged paint is sprayed on the surface of the golf ball to give a golf ball which has been coated uniformly. However, according to this method, a satisfactory coating can be formed on an article having a relatively large area, but the coating efficiency is inferior for an article having a relatively small area such as a golf ball, and thus at least twice as much paint is required in comparison with the air gun system.
Further, there is also suggested a coating method comprising spraying a charged paint over a golf ball moving on the circumference of a circle from the center part of an electrostatic coater.
However, according to this method, the charged paint is attracted to metal needles supporting the golf ball and, therefore, the lower half of the golf ball is hardly coated. Accordingly, in order to coat the whole golf ball uniformly, the golf ball must be turned over after moving around on the circumference of the circle and moved on the circumference of the circle one more time. Thus, the coating efficiency was good but producibility is low.
As described above, the conventional method for coating a golf ball has the problem that a coated film is not formed uniformly and the coating efficiency of the paint is inferior. Further, methods having good coating efficiency lack in producibility.